Much lower rate than previously reported

Two-thirds of athletes who have had reconstructive surgery to repair an anterior cruciate ligament (ACL) tear have not returned to competitive sports 12 months after surgery, according to a new Australian study reported in the American Journal of Sports Medicine.1 The findings are in sharp contrast to earlier studies showing a much higher rate of return to sports at the 1-year mark post-surgery.

As many parents know, anterior cruciate ligament (ACL) injuries are increasingly common among youth athletes, particularly girls, playing sports - such as soccer, basketball, football, and lacrosse - that involve a lot of cutting, jumping and pivoting.

Reconstructive surgery of the ACL, followed by an extensive rehabilitation program emphasizing early weightbearing and the immediate commencement of exercises to restore knee range of motion and muscle strength, can allow athletes to return to sport after medical clearance between 6 to 12 months postoperatively, with most targeting a return to sports within 12 months after surgery.

But, while athletes are typically advised that they will require a break from
sport
of approximately 6 to 12 months for full recovery of knee function
after ACL injury and surgery, the study suggests that, if a successful
return to sport is defined as a return to the preinjury sports
participation level, many athletes will require a longer period of
postoperative rehabilitation to ensure a successful return to sport than previously thought.

"The bottom line is that the knee is not normal, even 12 months after surgery," says Dr. Darren Johnson, Professor and Chairman of the Department of Orthopaedic Surgery and Director of Sports Medicine at the University of Kentucky School of Medicine. "When the knee is ready [for a return to sports] is extremely variable between patients. The pressure [on kids] to return to early in sports from all parties - kid, parent, coaches, friends, and society in general - is very high. Kids need to hold back until the knee is ready."

Study participants

Researchers at La Trobe (Aus.) University's Musculoskeletal Research Centre studied athletes who had participated in competitive level Australian football, basketball, soccer and netball (a sport similar to basketball played by Australian women) before their ACL injury and who then had arthroscopic ACL reconstructive surgery performed by the same surgeon between May 2003 and December 2008.

The study participants had all followed the same rehabilitation program after surgery (weightbearing the first postoperative day, quadriceps strengthening during the first 3 months postoperatively, straight-line running beginning at 12 weeks, progressing to sport-specific drills at 16 weeks), and then been cleared by the surgeon to return to sports based on completion of the full rehabilitation program, full knee range of motion, a stable knee, functional quadriceps control, and no fluid in the knee.

Key study findings

When the athletes returned at 12 months:

only 33% of the athletes had attempted to play competitive sport at their preinjury level

two-thirds had returned to some form of sports participation

men were more likely than women to have returned to preinjury competitive sports, and

those who participated in seasonal sports were more likely to return to competitive sport than those who participated in nonseasonal competition.

Study findings (detail)

Twelve months after ACL reconstruction surgery:

Only one-third of athletes (33.4%) had even attempted to return to sport at their pre-injury level;

Another one third (33.6%) had attempted training and/or modified competition;

The remaining one-third (33.0%) had not attempted to train for or play sport postoperatively;

Of the two-thirds of the study participants who had not attempted full competition:

47% indicated that they were planning to return to sport

12% had given up participation for reasons other than the knee;

13% had given up participation because of knee function; and

25 % did not report whether they intended to return to competitive sport

37% of men had attempted full competition in their preinjury sport versus 26% of women, consistent with an earlier study suggesting that female athletes may take longer to return to sport after an ACL injury, but women expressed an intention to return to sport at the same rate as men.

Patients achieving a good functional outcome (normal or near normal knee function) were no more likely to have attempted to return to full competition than patients with a poorer functional outcome.

Participants who played seasonal sports (sports played continuously for 8 weeks or greater followed by a distinct period where competition ceased) were significantly more likely than participants who played sports in year-round competition to have returned to full competition. Although the reasons for the difference were not clear, the study authors speculated that it might be the result of the fact that a seasonal competition gives a more definitive target date for returning to sport than a year-round sport, where the absence of a distinct season may reduce motivation for returning to sport by a specific date (e.g. the first game of the season).

There was a discrepancy between the physical rehabilitation outcomes (e.g. knee range of motion, stability, hop tests) and the return-to-sport rate, with no relationship between knee function and return-to-sport rate using one knee function test, while those with a hop limb symmetry index of less than 85% significantly less likely to have attempted sport when compared with patients with a limb symmetry index of 85% or more.

Effect of psychological factors

Earlier studies suggested a link between psychological factors and return to sport after ACL reconstruction. Two showed that patients up to 4 years post-ACL reconstruction surgery reported a fear of reinjury, with patients exhibiting a higher fear of reinjury less likely to have returned to their preinjury level of sports participation when compared with patients with a lower fear of reinjury. A third study showed that athletes who had returned to their preinjury level of sports participation level at 12 months after ACL reconstruction surgery scored significantly higher on a test assessing confidence, emotions and risk appraisal.

Based on these studies and their new findings, the authors suggested that further investigation of psychological functioning after ACL reconstruction surgery may be warranted.

Lower rate of return to sport reported

The return-to-sport rate reported in the study was sharply lower than in previous studies, which reported a return-to-sport rate of 75% and a return to competitive sport rate of 64%. The study's authors suggested that the lower rate may be explained by the fact that return to sport in their study was to the pre-injury level of competition, while earlier studies did not specify whether participants returned to either their pre-injury level of competition, or even to their preinjury sport and thus may have overestimated the return-to-competitive sport rate.

"Surgery is the easy part," says Dr. Johnson. "[It is the] rehabilitation that is the hard
part. It is a mentally and physically a challenge for young athletes
who, for the most part, have never had to go anything like it."